Method for obtaining intermediate resonance factor in reactor multigroup nuclear database

Abstract

The invention relates to a method for obtaining an intermediate resonance factor in a reactor multigroup nuclear database. On the basis of a free gas model, a continuum energy neutron scattering matrix expression Sigma<r, s, T> (E->E') of the resonance absorption nuclide relevant to the temperature TK is obtained through formula derivation; a neutron slowing down equation is solved on the basis of the continuum energy neutron scattering matrix at the temperature TK to obtain the neutron-flux density at the temperature TK; the multigroup adsorption cross section of the resonance absorption nuclide at the temperature TK is further worked out through group merging calculation; the intermediate resonance factor is finally obtained through the intermediate resonance factor calculation; and an intermediate resonance factor multinomial coefficient using the temperature and the background cross section as independent variables is obtained by a least squares fitting method. The method provided by the invention has the advantages that the intermediate resonance factor after the intermediate resonance factor calculation is more accurate; the calculation precision and the calculation efficiency of the intermediate resonance factor are improved; and finally, in the reactor physical calculation, the resonance calculation precision is improved, and the resonance calculation speed is accelerated.

Description

technical field [0001] The invention relates to the field of nuclear reactor multi-group nuclear database and reactor physics calculation, and in particular relates to a method for obtaining an intermediate resonance factor in a reactor multi-group nuclear database. Background technique [0002] In order to meet the needs of high-fidelity resonance calculations in numerical reactors, it is crucial to provide accurate intermediate resonance factors in multi-swarm databases. [0003] At present, for the intermediate resonance factor, the calculation method of the intermediate resonance factor proposed in the internationally popular evaluation nuclear database processing program NJOY (hereinafter referred to as NJOY) is widely used. With the increasing requirements of reactor resonance calculation, many models and applicability of this method in calculating intermediate resonance factors can no longer meet the requirements. [0004] The calculation method of the intermediate r...

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Problems solved by technology

[0028] It can be seen from the above steps that this method will involve solving the neutron moderation equation, but the current traditional method when solving the neutron moderation equation, the model describing neutron elastic scattering is the progressive scattering kernel model, which ignores the resonant kernel The resonant upscattering of the element increases the resonant absorption, which leads to the inaccuracy of the calculated fine energy spectrum, further leads to the inaccuracy of the multi-group section, and finally makes the intermediate resonance factor inaccurate; on the other hand, from the above knowledge, the intermediate resonance factor It is a function of energy group, background cross-section, and temperature. In the calculation of full-reactor resonance, the background cross-section and temperature are constantly changing with the deepening of reactor burnup. This method can be used to continuously repeat the above steps according to the actual situation in the reactor. Online calculation Intermediate resonance factor, but slows computation time due to large full stack size

And if the scattering on the resonance is considered, the iterative method will be used to solve the moderating equation, which will also increase the calculation time sharply, which is extremely unfavorable for the calculation of the whole stack resonance

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